The present invention relates to local access to data while roaming with a mobile telephony device and, more particularly, but not exclusively to such access for Internet surfing and like data uses.
Data roaming in GSM and other 3G networks is based on the concept that all data traffic is routed to the home network first, and then to the final destination. The SGSN (Serving GPRS Support Node) network core element in the roaming (visited) network receives the data traffic from the base station/base station controller, performs DNS resolution, and routes the traffic to the home network GGSN (Gateway GPRS Support Node). The GGSN allocates an IP address for the mobile device, and connects the session to the service—the Internet, the so-called walled garden or home portal network, or any other service. The GGSN may also performs charging for the data service, and charging may be either postpaid, via data records, CDRs or OCS—an Online Charging System, or may be prepaid, achieved by interfacing with a prepaid system. Charging can also be triggered by the SGSN at the visited network, using CAMEL triggers sent directly to the home charging system. Such is mainly used for prepaid.
In the fourth generation or 4G LTE/EPC (4G) network, the situation remains basically the same. All roaming data is still to be directed to the home network. In LTE voice is considered data as well, as LTE uses VoIP solutions such as SIP and IMS. However voice originated calls in roaming, that is MO calls, or Mobile originated calls, are not necessarily routed to the home network first. Instead, they may be routed to the destination directly from the roaming network. Such direct routing actually preserves the situation in 2G/3G networks, where MO calls in roaming are also not routed to the home network. Direct routing works by building into LTE networks a configuration known as Local Breakout, where data is identified as voice data, according to the APN (Access Point Name) of the voice application, and following identification is handled solely by the local network. However data not identified as voice data continues to be sent to the home network as before, leading to greater cost, lower efficiency and lower quality of service.
The present inventors consider that the current situation in which data traffic does go to the home network is going to change, as more data traffic is used by roamers.
Home routing of data traffic indeed creates a severe quality of service (QoS) problem for the data traffic, due to the additional distance it passes. In addition, the mobile operator is charged by the international carrier for a GRX service (GPRS exchange routing).
As mentioned, LTE/EPC indicates the fourth generation (4G) of mobile network to evolution. LTE (Long Term Evolution) concentrates on the radio part of the network, while EPC (Evolved Packet Network) refers to the all-IP next generation core network. The network architecture may drastically change while moving to all-IP. The traditional 2G/3G features of MSC/VLR and HLR are expected to disappear, replaced by new network components: MME, Service GW and PDN GW.
The 3GPP LTE roaming standardization uses different architectures respectively for home routing and local breakout. Home routing requires all data traffic to go to the home network first, and then to the destination, as in the case of the legacy GSM and 3G. However since voice calls are data too (except for the CS fallback case), 3GPP preserves the current mode for roaming MO calls (Mobile Originated) calls, so that the MO calls are not routed to the home network first. For this reason, the local breakout mode was defined, where the visited network (VPMN) enables a local exit of voice sessions. The local exit requires the VPMN to distinguish between voice and data sessions, and apply different routing rules, per the specific home network.
Voice calls originating in the roaming network are thus not routed to the home network, unless of course this is the actual destination. Nevertheless, as data, such as packets for Internet browsing, is always given a destination at the home network, such data is necessarily routed to the home network.
The 3GPP standard solution for charging the local breakout scenario is relatively complex. The system requires that the PCEF unit, the Policy and Charging Evaluation Function, at the visited network, which has the home network charging rules loaded, communicates with the home OCS (On-line Charging System) that does the actual charging. For the local breakout scenario, the home OCS may perform real-time charging according to the visited network tariff plans and charges. In LTE networks the tariff plans and policies may dynamically change, and that requires the home network OCS to adapt in real time as well.
Alcatel-Lucent (ALU) identified this problematic situation, and published an article proposing an improved solution. The paper, “Online Charging in the Roaming LTE/EPC Network”, was published in Bell Labs Technical Journal 15(1), pages 115-132, at 2010. ALU proposes adding a v-OCS, an additional OCS entity at the visited network which serves inbound roamers, and mediates with the home OCS. The v-OCS may be the focal point for local charging, according to the VPMN charging plans, but always in communication with the h-OCS. The ALU solution imposes a new architecture at the VPMN and new interfaces to the home OCS, Ro′ and Rc′, which are not standardized yet, and even more problematically, which requires modification to the home OCS as well.